The engine consists of a fixed cylinder and a moving piston. The expanding combustion gases push the piston, which in turn rotates the crankshaft. Ultimately, through a system of gears in the powertrain, this motion drives the vehicle’s wheels.

An engine is some machine that converts energy from a fuel to some mechanical energy, creating motion in the process. Engines – such as the ones used to run vehicles – can run on a variety of different fuels, most notably gasoline and diesel in the case of cars